Sensor module, touch panel, and electronic device

The present application is a continuation of International application No. PCT/JP2023/039277, filed Oct. 31, 2023, which claims priority to Japanese Patent Application No. 2022-181684, filed Nov. 14, 2022, the entire contents of each of which are incorporated herein by reference.

The present disclosure relates to a sensor module including a sensor that detects deformation of a member.

Patent Document 1 describes a touch sensor including a housing, a plate, a press detecting sensor, and a position detecting sensor. The position detecting sensor, the press detecting sensor, and the plate are arranged in this order in a positive direction of a Z axis. Outer peripheral ends of the plate, the press detecting sensor, and the position detecting sensor are fixed to the housing. The position detecting sensor detects a position touched by a user on the plate.

The press detecting sensor detects a force applied to the plate by the user. The press detecting sensor includes a piezoelectric film, a first piezoelectric detection electrode, and a second piezoelectric detection electrode. The piezoelectric film is located between the first piezoelectric detection electrode and the second piezoelectric detection electrode. Each of the first piezoelectric detection electrode and the second piezoelectric detection electrode has an annular shape as viewed in a thickness direction of the touch sensor. Each of the first piezoelectric detection electrode and the second piezoelectric detection electrode is provided at an outer peripheral edge portion of the plate.

In a field of the touch sensor described in Patent Document 1, it is desired that a sensor which detects deformation of a member easily detects the deformation of the member.

An object of the present disclosure is to provide a sensor module in which a sensor which detects deformation of a member easily detects the deformation of the member.

A sensor module according to an embodiment of the present disclosure includes: an elastic member; a piezoelectric sensor which includes a piezoelectric film, one or more first electrodes, and one or more second electrodes; and a touch sensor which includes a plurality of transmission electrodes and a plurality of reception electrodes, the elastic member, the piezoelectric sensor, and the touch sensor are arranged in this order in a negative direction of a Z axis, each of the one or more first electrodes are on a positive side of the Z axis with respect to the piezoelectric film, each of the one or more second electrodes are on a negative side of the Z axis with respect to the piezoelectric film, the piezoelectric sensor is constructed to output a first signal when the elastic member is deformed, each of the plurality of transmission electrodes are on the negative side of the Z axis with respect to the plurality of reception electrodes, the touch sensor is constructed to output a second signal on the basis of a capacitance value when a capacitance is generated between the plurality of transmission electrodes and the plurality of reception electrodes, the plurality of transmission electrodes include a plurality of first non-overlapping portions that do not overlap the plurality of reception electrodes as viewed in a Z axis direction, the plurality of reception electrodes include a plurality of second non-overlapping portions that do not overlap the plurality of transmission electrodes as viewed in the Z axis direction, and the plurality of first non-overlapping portions or the plurality of second non-overlapping portions do not overlap the one or more first electrodes and the one or more second electrodes as viewed in the Z axis direction.

According to the sensor module according to the embodiment of the present disclosure, the sensor which detects deformation of a member easily detects the deformation of the member.

Hereinafter, a sensor moduleaccording to a first embodiment of the present disclosure will be described with reference to the drawings.is an exploded perspective view of the sensor module. In, the description of adhesive layers G, G, G, and Gis omitted.is a perspective view of the sensor moduleas viewed in a positive direction of a Y axis.is a view of the piezoelectric sensoras viewed in a negative direction of a Z axis.is a view of a piezoelectric filmas viewed in the negative direction of the Z axis.is a view of a touch sensoras viewed in the negative direction of the Z axis.is a view of a plurality of reception electrodes, a plurality of transmission electrodes, and a piezoelectric sensoras viewed in the negative direction of the Z axis.is a view illustrating a case where a usertouches an elastic member.

In the present embodiment, directions are defined as follows. As illustrated in, the Z axis direction is a direction in which the elastic member, the piezoelectric sensor, and the touch sensorare arranged. A positive direction of the Z axis is a direction in which the touch sensor, the piezoelectric sensor, and the elastic memberare arranged in this order. The negative direction of the Z axis is a direction in which the elastic member, the piezoelectric sensor, and the touch sensorare arranged in this order. An X axis direction is a direction orthogonal to the Z axis direction. A Y axis direction is a direction orthogonal to the Z axis direction and the X axis direction.

The sensor moduleis used in, for example, an electronic device such as a smartphone. As illustrated in, the sensor moduleincludes the elastic member, the piezoelectric sensor, and the touch sensor.

The elastic memberis formed of, for example, resin. As illustrated in, the elastic memberhas a plate shape having a long side extending along the X axis and a short side extending along the Y axis. The elastic memberhas elasticity. The elastic memberis deformed by a force applied to the elastic member. For example, the userpresses the elastic memberin the negative direction of the Z axis. The elastic memberis deformed by the force which is applied to the elastic memberin the negative direction of the Z axis, so as to protrude in the negative direction of the Z axis.

As illustrated in, the piezoelectric sensorhas a rectangular shape which has a long side extending along the X axis and a short side extending along the Y axis. As illustrated in, the piezoelectric sensorincludes the piezoelectric film, a first electrode, a second electrode, a first dielectric layer, the adhesive layer G, the adhesive layer G, and a detection circuit (not illustrated).

As illustrated in, the piezoelectric filmhas a sheet shape which has a long side extending along the X axis and a short side extending along the Y axis. As illustrated in, the piezoelectric filmincludes a piezoelectric film first main surface SFand a piezoelectric film second main surface SFarranged along the Z axis. The piezoelectric film first main surface SFand the piezoelectric film second main surface SFare arranged in this order in the negative direction of the Z axis.

The piezoelectric filmgenerates a charge according to a deformation amount of the piezoelectric film. A polarity of the charge generated when the piezoelectric filmis stretched in the X axis direction is opposite to a polarity of the charge generated when the piezoelectric filmis stretched in the Y axis direction. Specifically, the piezoelectric filmis a film formed of a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA), particularly poly-L-lactic acid (PLLA). A main chain of the PLLA has a helical structure. The PLLA has piezoelectricity in which molecules are oriented when uniaxial stretching is performed. In the present embodiment, a material of the piezoelectric filmis polylactic acid. The piezoelectric filmhas a piezoelectric constant of d. As illustrated in, a uniaxial stretching direction OD of the piezoelectric filmforms an angle of 45 degrees with respect to the X axis direction and the Y axis direction. The 45 degrees include, for example, an angle including about 45 degrees±10 degrees. As a result, the piezoelectric filmgenerates a charge when the piezoelectric filmis stretched in the X axis direction or the Y axis direction. The piezoelectric filmgenerates a positive charge when the piezoelectric filmis stretched in the X axis direction, for example. The piezoelectric filmgenerates a negative charge when the piezoelectric filmis stretched in the Y axis direction, for example. A magnitude of the charge depends on a differential value of the deformation amount of the piezoelectric filmdue to stretching or compression.

The first electrodeis a reference electrode connected to a reference potential. The first electrodeis located on the positive side of the Z axis with respect to the piezoelectric film. The first electrodeis provided on the piezoelectric film first main surface SF. The first electrodeis fixed to the piezoelectric film first main surface SFby an adhesive (not illustrated) such as an optically clear adhesive (OCA). A material of the first electrodeis, for example, indium tin oxide (ITO).

The first electrodeincludes three types of portions having different shapes. Specifically, as illustrated in, the first electrodeincludes a plurality of first electrode first portionsA, a plurality of first electrode second portionsB, and a plurality of first electrode third portionsC.

In the present embodiment, each of the plurality of first electrode first portionsA has a square shape as viewed in the Z axis direction. The plurality of first electrode first portionsA have the same shape as viewed in the Z axis direction. The plurality of first electrode first portionsA are arranged in a matrix on the piezoelectric film first main surface SF. Specifically, as illustrated in, a plurality of sets ST of the plurality of first electrode first portionsA arranged along the X axis are provided on the piezoelectric film first main surface SF. The plurality of sets are arranged at equal intervals along the Y axis. The plurality of first electrode first portionsA are not in contact with each other. The plurality of first electrode first portionsA do not overlap each other as viewed in the Z axis direction.

As illustrated in, each of the plurality of first electrode second portionsB extends along the X axis. A length of each of the plurality of first electrode second portionsB in the Y axis direction is shorter than a length of each of the plurality of first electrode first portionsA in the Y axis direction. As illustrated in, each of the plurality of first electrode second portionsB electrically connects two adjacent first electrode first portionsA of the plurality of first electrode first portionsA arranged along the X axis.

As illustrated in, each of the plurality of first electrode third portionsC extends along the Y axis. Each of the plurality of first electrode third portionsC electrically connects two adjacent first electrode first portionsA of the plurality of first electrode first portionsA arranged along the Y axis. A length of each of the plurality of first electrode third portionsC in the X axis direction is shorter than a length of each of the plurality of first electrode first portionsA in the X axis direction.

As illustrated in, the first dielectric layerhas a sheet shape which has a long side extending along the X axis and a short side extending along the Y axis. The first dielectric layeris located on the negative side of the Z axis with respect to the piezoelectric film. The first dielectric layerincludes a first dielectric layer first main surface SFand a first dielectric layer second main surface SFarranged along the Z axis. The first dielectric layer first main surface SFand the first dielectric layer second main surface SFare arranged in this order in the negative direction of the Z axis. The first dielectric layerhas dielectric properties. A material of the first dielectric layeris polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), or the like.

The second electrodeis a signal electrode. As illustrated in, the second electrodeis located on the negative side of the Z axis with respect to the piezoelectric film. The second electrodeis provided on the first dielectric layer first main surface SF. The second electrodeis fixed to the first dielectric layer first main surface SFby an adhesive (not illustrated) such as OCA. As illustrated in, the second electrodeoverlaps the first electrodeas viewed in the Z axis direction. A material of the second electrodeis, for example, ITO.

As illustrated in, the second electrodeincludes three types of portions having different shapes, similarly to the first electrode. The second electrodeincludes a plurality of second electrode first portionsA, a plurality of second electrode second portionsB, and a plurality of second electrode third portionsC.

Similarly to the plurality of first electrode first portionsA, the plurality of second electrode first portionsA are arranged in a matrix on the first dielectric layer first main surface SF(see). The plurality of second electrode first portionsA overlap the plurality of first electrode first portionsA as viewed in the Z axis direction, respectively. The other configuration of each of the plurality of second electrode first portionsA is the same as the configuration of the plurality of first electrode first portionsA, and thus the description thereof will be omitted.

Each of the plurality of second electrode second portionsB electrically connects two adjacent second electrode first portionsA of the plurality of second electrode first portionsA arranged along the X axis. The plurality of second electrode second portionsB overlap the plurality of first electrode second portionsB as viewed in the Z axis direction, respectively. The other configuration of each of the plurality of second electrode second portionsB is the same as the configuration of the plurality of first electrode second portionsB, and thus the description thereof will be omitted.

Each of the plurality of second electrode third portionsC electrically connects two adjacent second electrode first portionsA of the plurality of second electrode first portionsA arranged along the Y axis. The plurality of second electrode third portionsC overlap the plurality of first electrode third portionsC as viewed in the Z axis direction, respectively. The other configuration of each of the plurality of second electrode third portionsC is the same as the configuration of the plurality of first electrode third portionsC, and thus the description thereof will be omitted.

As illustrated in, the adhesive layer Gis located between the elastic memberand the piezoelectric film. The adhesive layer Gis located around the first electrode. The piezoelectric filmis fixed to the elastic memberby the adhesive layer G

As illustrated in, the adhesive layer G(first adhesive layer) is located between the first dielectric layerand the piezoelectric film. The adhesive layer Gis located around the second electrode. The first dielectric layeris fixed to the piezoelectric filmby the adhesive layer G

The detection circuit is electrically connected to the first electrodeand the second electrode. The detection circuit converts the charge generated by the piezoelectric filminto a voltage signal. The detection circuit AD-converts the voltage signal to generate a first signal which is a digital signal.

The piezoelectric sensoroutputs the first signal corresponding to the deformation of the elastic member. As illustrated in, the piezoelectric sensoris fixed to the elastic memberby the adhesive layer G. As a result, the piezoelectric sensoris deformed along with the deformation of the elastic member. The piezoelectric sensoroutputs the first signal corresponding to the deformation of the piezoelectric sensor. The piezoelectric sensoroutputs the first signal on the basis of a potential difference between the first electrodeand the second electrode.

As illustrated in, the touch sensorhas a plate shape which has a long side extending along the X axis and a short side extending along the Y axis. Specifically, the touch sensoris a capacitive touch sensor. As illustrated in, the touch sensorincludes a second dielectric layer, a plurality of reception electrodes, a plurality of transmission electrodes, a third dielectric layer, the adhesive layer G, the adhesive layer G, a transmission circuit, and a reception circuit.

As illustrated in, the second dielectric layerhas a sheet shape which has a long side extending along the X axis and a short side extending along the Y axis. As illustrated in, the second dielectric layeris located on the negative side of the Z axis with respect to the first dielectric layer. Therefore, the second dielectric layeris located on the negative side of the Z axis with respect to the piezoelectric film. The second dielectric layerincludes a second dielectric layer first main surface SFand a second dielectric layer second main surface SFarranged along the Z axis. The second dielectric layer first main surface SFand the second dielectric layer second main surface SFare arranged in this order in the negative direction of the Z axis. The other configuration of the second dielectric layeris the same as the configuration of the first dielectric layer, and thus the description thereof will be omitted.

As illustrated in, each of the plurality of reception electrodesis provided on the second dielectric layer first main surface SF. Each of the plurality of reception electrodesis fixed to the second dielectric layer first main surface SFby an adhesive (not illustrated) such as OCA. As illustrated in, each of the plurality of reception electrodesextends along the Y axis. The plurality of reception electrodesare arranged at equal intervals along the X axis. The plurality of reception electrodesare not in contact with each other. The plurality of reception electrodesdo not overlap each other as viewed in the Z axis direction. A material of each of the plurality of reception electrodesis, for example, ITO.

Each of the plurality of reception electrodesincludes two types of portions having different shapes. Specifically, each of the plurality of reception electrodesincludes a plurality of reception electrode first portionsA and a plurality of reception electrode second portionsB.

As illustrated in, each of the plurality of reception electrode first portionsA has a square shape as viewed in the Z axis direction. The plurality of reception electrode first portionsA have the same shape as viewed in the Z axis direction. Similarly to the plurality of first electrode first portionsA, the plurality of reception electrode first portionsA are arranged in a matrix on the second dielectric layer first main surface SF. In the present embodiment, the plurality of reception electrode first portionsA overlap the plurality of first electrode first portionsA as viewed in the Z axis direction, respectively (see).

Each of the plurality of reception electrode second portionsB extends along the Y axis as illustrated in. A width of each of the plurality of reception electrode second portionsB in the X axis direction is shorter than a width of each of the plurality of reception electrodesin the X axis direction. Each of the plurality of reception electrode second portionsB electrically connects two adjacent reception electrode first portionsA of the plurality of reception electrode first portionsA arranged along the Y axis. In the present embodiment, the plurality of reception electrode second portionsB overlap the plurality of first electrode second portionsB and the plurality of second electrode second portionsB as viewed in the Z axis direction, respectively.

As illustrated in, the third dielectric layeris located on the negative side of the Z axis with respect to the second dielectric layer. The third dielectric layerincludes a third dielectric layer first main surface SFand a third dielectric layer second main surface SFarranged along the Z axis. The third dielectric layer first main surface SFand the third dielectric layer second main surface SFare arranged in this order in the negative direction of the Z axis. The other configuration of the third dielectric layeris the same as the configuration of the second dielectric layer, and thus the description thereof will be omitted.

The plurality of transmission electrodesare located on the negative side of the Z axis with respect to the plurality of reception electrodes. The plurality of transmission electrodesare provided on the third dielectric layer first main surface SF. Each of the plurality of transmission electrodesis fixed to the third dielectric layer first main surface SFby an adhesive (not illustrated) such as OCA. As illustrated in, each of the plurality of transmission electrodesextends along the X axis. The plurality of transmission electrodesare arranged at equal intervals in the Y axis direction. The plurality of transmission electrodesis not in contact with each other. The plurality of transmission electrodesdo not overlap each other as viewed in the Z axis direction. A material of each of the plurality of transmission electrodesis, for example, ITO.

Each of the plurality of transmission electrodesincludes two types of portions having different shapes. Each of the plurality of transmission electrodesincludes a plurality of transmission electrode first portionsA and a plurality of transmission electrode second portionsB.

As illustrated in, each of the plurality of transmission electrode first portionsA has a square shape as viewed in the Z axis direction. The plurality of transmission electrode first portionsA have the same shape as viewed in the Z axis direction. Similarly to the plurality of first electrode first portionsA, the plurality of transmission electrode first portionsA are arranged in a matrix on the third dielectric layer. In the present embodiment, each of the plurality of transmission electrode first portionsA does not overlap the first electrodeand the second electrodeas illustrated in. The plurality of transmission electrode first portionsA do not overlap the plurality of reception electrodes.

Each of the plurality of transmission electrode second portionsB has a shape extending along the X axis. A length of each of the plurality of transmission electrode second portionsB in the Y axis direction is shorter than a length of each of the plurality of transmission electrode first portionsA in the Y axis direction. Each of the plurality of transmission electrode second portionsB electrically connects two adjacent transmission electrode first portionsA of the plurality of transmission electrode first portionsA arranged along the X axis.

In the present embodiment, as illustrated in, parts of the plurality of transmission electrode second portionsB overlap the plurality of reception electrode second portionsB as viewed in the Z axis direction, respectively. More specifically, a center of each of the plurality of transmission electrode second portionsB in the X axis direction and a vicinity thereof overlap with the reception electrode second portionB. That is, as illustrated in, the plurality of transmission electrodesinclude a plurality of first overlapping portions Toverlapping the plurality of reception electrodesas viewed in the Z axis direction. In addition, the plurality of transmission electrodesinclude a plurality of first non-overlapping portions NTthat do not overlap the plurality of reception electrodesas viewed in the Z axis direction. Each of the plurality of first non-overlapping portions NTis a portion other than the plurality of first overlapping portions Tin the plurality of transmission electrodes. Therefore, in the example illustrated in, the plurality of first non-overlapping portions NTincludes the plurality of transmission electrode first portionsA and both ends of the plurality of transmission electrode second portionsB in the X axis direction, respectively.

In the present embodiment, as illustrated in, the plurality of first non-overlapping portions NTdo not overlap the first electrodeand the second electrodeas viewed in the Z axis direction. Each of the plurality of transmission electrode first portionsA and both ends of each of the plurality of transmission electrode second portionsB in the X axis direction do not overlap the first electrodeand the second electrodeas viewed in the Z axis direction.

In the above configuration, as illustrated in, it is sufficient that a center of gravity Gr of each of at least the plurality of transmission electrode first portionsA does not overlap the first electrodeand the second electrode. Therefore, a portion other than the center of gravity Gr in each of the plurality of transmission electrode first portionsA may overlap the first electrodeand the second electrode. In the present embodiment, unless otherwise specified, the center of gravity Gr means a center of gravity as viewed in the Z axis direction. Therefore, the center of gravity Gr in the present embodiment is a center of gravity in a two-dimensional plane.

As illustrated in, the adhesive layer Gis located between the first dielectric layerand the second dielectric layer. The second dielectric layeris fixed to the first dielectric layerby the adhesive layer G. The adhesive layer Gis located around the plurality of reception electrodes.

As illustrated in, the adhesive layer G(second adhesive layer) is located between the second dielectric layerand the third dielectric layer. The third dielectric layeris fixed to the second dielectric layerby the adhesive layer G. The adhesive layer Gis located around the plurality of transmission electrodes.

The transmission circuittransmits a signal (hereinafter, referred to as a transmission signal) to each of the plurality of transmission electrodes. The transmission circuitis, for example, an electric circuit including a multiplexer. The multiplexer sequentially selects the plurality of transmission electrodesone by one. The transmission circuittransmits a transmission signal to one transmission electrodeselected by the multiplexer among the plurality of transmission electrodes.

The reception circuitreceives a signal (hereinafter, referred to as a reception signal) from each of the plurality of reception electrodes. The reception circuitis an electric circuit including a multiplexer. The multiplexer sequentially selects the plurality of reception electrodesone by one. The reception circuitreceives the reception signal from one reception electrodeselected by the multiplexer among the plurality of reception electrodes. As a result, the touch sensoroutputs a second signal on the basis of a capacitance value of a capacitance generated between the plurality of transmission electrodesand the plurality of reception electrodes. The touch sensortransmits the second signal to an arithmetic circuit.

The arithmetic circuitspecifies a position touched by the useron the elastic member, on the basis of the second signal. Specifically, the arithmetic circuitcalculates the capacitance value of the capacitance generated between the plurality of transmission electrodesand the plurality of reception electrodes, on the basis of the second signal. The arithmetic circuitspecifies the position touched by the useron the elastic member, on the basis of the calculated capacitance value.

For example, as illustrated in, when the userdoes not touch the elastic member, a capacitance having a capacitance value Cis generated between one transmission electrodeamong the plurality of transmission electrodesand one reception electrodeamong the plurality of reception electrodes. Here, as illustrated in, the usertouches the elastic member. At this time, a capacitance having a capacitance value Cis generated between the userand one transmission electrode(hereinafter, referred to as a detection transmission electrode) among the plurality of transmission electrodes. At this time, due to the capacitance generated between the userand the detection transmission electrode, a capacitance having a capacitance value Cdifferent from the capacitance value Cis generated between one reception electrode(hereinafter, referred to as a detection reception electrode) among the plurality of reception electrodesand the detection transmission electrode. The capacitance value Cis less than the capacitance value C. At this time, the arithmetic circuitspecifies, as the detection transmission electrode, one transmission electrode, in which the capacitance having the capacitance value Cis generated between the transmission electrodeand the plurality of reception electrodes, among the plurality of transmission electrodes. In addition, the arithmetic circuitspecifies, as the detection reception electrode, one reception electrode, in which the capacitance having the capacitance value Cis generated between the reception electrodeand the plurality of transmission electrodes, among the plurality of reception electrodes. The arithmetic circuitdetermines, as the position touched by the useron the elastic member, a position at which the detection transmission electrode and the detection reception electrode intersect as viewed in the Z axis direction.